Is sexual assault more common among r-strategist species vs K-strategist species

Factual Questions
1

In ecology, r/K selection theory relates to the selection of combinations of traits in an organism that trade off between quantity and quality of offspring. The focus on either an increased quantity of offspring at the expense of reduced individual parental investment of r-strategists, or on a reduced quantity of offspring with a corresponding increased parental investment of K-strategists, varies widely, seemingly to promote success in particular environments.

So in some species (like sea turtles) they have a lot of children with very little/no parental investment and in other species (whales) they have a few children with more parental investment. Its a trade off and it depends on the environment which determines if its best to have a bunch of kids with no investment, or a small number of kids with large amounts of investment.

I don’t know if this ties into the r/K dynamic, but what I’m wondering is that males have an evolutionary advantage by having large numbers of children with no paternal investment. This can be done consensually, but this also describes non-consensual sexual assault. Some males sexually abuse large numbers of females among the human species, which is a K species.

Is it known if r-strategist species have higher rates of sexual abuse committed by males than K-strategist species, or does the reproduction type of a species not have a role in whether the males are more prone to sexual assault or not?

Is it known what factors do increase the rates of sexual abuse among males in a species? Like ducks supposedly have extremely high rates of sexual abuse. Why would male ducks be more likely to commit sexual assault than (as an example) life forms like pigeons or wolves?

2

How able the females are able to defend themselves is an obvious one; porcupines have zero issue for example, because unless the female cooperates the male would end up a pincushion. Or among our close relatives there’s the difference between common chimpanzees and bonobos; among bonobos the females form alliances like the males and so sexual or other abuse seldom happens because the male who tries it gets mobbed. Meanwhile common chimpanzees are like humans in the females don’t form alliance groups, and abuse is common because the female in question is on her own.

Also, I’ll point out that sexual cannibalism is much more common in female animals than male ones, a rather extreme form of sexual abuse. Fortunately not normally an issue with humans, but it is among a number of animals. Notably, one reason for it is size:

Sexual cannibalism occurs more often among species with prominent sexual size dimorphism (SSD); extreme SSD likely drives this trait of sexual cannibalism in spiders.[10] It also sometimes occurs in some anacondas, especially the green anaconda (Eunectes murinus), where females are larger than the males.

3

It’s tricky even defining the notion of “consent”, in most species, and without that, how do you define assault?

4

One problem with “forced copulation” a.k.a. “rape” is the possibility of causing sufficient injury to the female she is unable to complete her part of the reproductive cycle and deposit eggs/give birth. Male mallard ducks, for instance, have been known to occasionally gang rape a female to the point she drowns. This does not improve reproductive success for anyone involved.

In some species the females are able to hold their own against males. I once saw a mare kick a wannabe stud in the genitals. The male horse almost fell down, was clearly in severe pain, and was only able to hobble away. (No, he didn’t try again). In many species of birds the female is bigger than the male. In raptors often notably so, such that the male is likely in more danger from the female than vice versa. On the other hand, bedbugs have a crazy system where it is, apparently, for the males to skip the vagina-equivalent and stab the females with their penis to reproduce, a “technique” called “traumatic insemination”. Biology can be crazy.

Anyhow - as bedbugs demonstrate this can be a strategy in a species but examining the rest of the animal kingdom shows it’s pretty rare as an exclusive method of making more of the same.

Reasons rape may not be effective at making more of a particular critter:

As mentioned - possibly of injuring the female to the point she doesn’t reproduce the rapist’s offspring, or is even killed (in which case she really won’t reproduce).

The MALE might be injured, perhaps to the point of impairing future reproductive ability. Pretty sure the porcupine species is rape free for obvious reasons. I can not imagine a male black widow spider trying “sexual assault” - not only is the female significantly larger, there’s a good chance she’s going to eat him anyway. If he leads with force he’s definitely going to be dinner. Female hawks tend to be about 1/3 bigger than the males and proportionately stronger, it’s pretty unlikely he’d try it and she could easily kill him if he pissed her off enough.

Some critters - female mallards, for example - have internal means that hamper insemination unless the female is willing and cooperative. Which is unlikely if she’s being forced.

Rape might occur when the female isn’t actually ready to conceive, before or after that narrow window when she might be more cooperative.

Rejection of the rapist’s offspring - this would seem to require a knowledge of how this biology works which, we assume, is limited to people but hey, we’re critters to. While there are women who keep children that are the product of rape others reject them, perhaps forcefully, which would work against rape as a reproductive strategy in humans. Wild animals sometimes reject offspring for no reason we can see so maybe that’s a reason, how would we ever know? (Really, we can only know this about humans)

But, beyond that - animals where hundreds or thousands of offspring are created and sent out into the world have an incentive to force conception because… why? They’re already producing gajillions of young, why risk anything at all to do more?

You tend to see rape where the chances for males successfully mating/reproducing are low, instances where risking the downsides listed above are worth more than never reproducing at all. I would think this would make rape more likely among the K-species where reproductive chances are limited and thus each is more valuable. r-Species where pretty much all males get a chance, particularly those where conception occurs outside the body (frogs and most fish, for example), it would be either less useful or even pointless.

5

Well… if the female tries to repeatedly get away from the male(s), kicks/claws/bites, changes position in a manner to make copulation more difficult… we might define that as assault.

We could use injury… except for species like bedbugs where a female being stabbed in a random part of her body cavity and injected with sperm seems to actually be the way the species reproduces. I’m not sure we can spot it in those cases, or of the question even actually applies to insects that only reproduced by impalement-on-penis.

6

Maybe, or maybe not. In a lot of species (squirrels come to mind), for instance, the females run away from the males at mating time, but that could just mean that they’re attracted to fast-running males and are trying to select for only the best partners. In other words, the female might be unwilling to mate with the males who don’t catch her, but willing to mate with the males who do.

I’m not sure what species’ females kick/claw/bite the males, but do they do that to all prospective partners?

7

Clearly, a lot depends on the species.

Not all species have “chase” as part of their mating rituals. In such cases the “trying to get away” thing might be a indicator. As would normal vs. not-normal behavior during mating.

I realize that there’s a tendency to say “don’t anthropomorphize animals” and not assume these things are unwilling, but neither should we take the stance that it’s entirely irrelevant or impossible for a female to be unwilling. I’m pretty sure female mallards drowned by males attempting to fuck them were NOT looking for that end.

8

FWIW, could go into the nature thread. I have 2 pairs of Robins at my place here, one territory centered on my unit the other on the pool area 50 yards away.

A 3rd male has been hanging around, saw him kind of stalking one of the females, which did NOT make the resident male happy at all, and he promptly chased the intruder away. The other resident did so as well yesterday. Not exactly “sexual assault” but definitely attempts at sneaking matings when the males’ attentions are elsewhere.

9

Right, I’m not saying that there’s no such thing as rape, among animals. I’m just saying that it’s extremely difficult for us to tell.

10

Right.

In the case of the two robin territories and the third male, the resident males may be unhappy but for all we know the females are voluntarily having affairs with the new guy on the block. Genetic testing of wild birds has shown that the male defending a territory isn’t always the father of all the babies in the nest. Sometimes not the father of any of them.

11

One issue here for birds, is that ducks are unusual in that the males have penises. The males of most bird species do not; they copulate by lining up their cloaca to transfer sperm from male to female. That requires cooperation by both partners, so rape is essentially impossible.

12

Today I learnt… honestly, this is totally new to me.

I know about the weirdness of duck reproduction, but I was not aware that cloaca/cloaca reproduction was a thing.

13

It is sometimes referred to as a “cloacal kiss”

14

Touchy subject, but…

It seems to me - that rape would be most common in this:

if the number of offspring over a lifetime is low, then the odds of not reproducing are high if the male is not aggressive. “Aggressive” can mean many things, from forcing himself on unwilling/uncooperative females, to avoiding and bypassing competing and possessive males that are trying to defend “their” females.

This contributes to the “size matters”. Aggressive males would tend to be the bigger sex, in order to win fights. Aggresiveness also allows physical domination of the female. A physically dominant female who can fight off males is less likely to reproduce - and reproduction is the end goal of nature.

There are a massive number of reproduction strategies. Larry Niven mentions “sneaky fuckers” in some of his science fiction stories. Males who cannot compete physically with the male with a harem, but will take advantage of his harem when he is otherwise occupied. There is no indication that consent is lacking. It also applies with monogamous species, as humans know well. The same may be true of robins…

Gang rapes are also a reproductive strategy. If the female only bears one offspring (or litter) at a time, and not many over a lifetime - then when a female is in heat, then the odds are better of fathering offspring by adding one’s own sperm to the mix if exclusivity is not an option. IIRC there are some species of monkeys where the female in heat willingly is taken by many males in the troop. Since it is a large troop rather than monogamous couples, every male in the group has an incentive to help in protecting and raising the offspring on the chance it may be theirs.

There’s a book by Jared Diamond, Why Is Sex Fun? which discusses a number of different reproduction strategies and the pro’s and con’s of each.

15

It also depends on the mechanism of sperm distribution.

Not so much sea turtles (they do have a penis) but the species that mate by both sexes dispersing their reproductive cells (sperm and eggs) into the water, a common method of fish and invertebrates. No point in rape there, as penetration is not required. Better to spend the energy on producing more and better swimming sperm.

That is the norm only in mammals. Many, may other types of animal it is the FEMALE that is larger. In raptors - hawks, eagles, owls, falcons, etc.- females are the larger sex, typically 30% larger. Larger birds can produce larger eggs with less risk to the hen.

As a comparison, humans are weakly dimorphic. In the United States, the average woman is about 5’3" and 170 pounds these days (77 kg and 162 cm). The average man is about 5’9" (175 cm) and weighs about 200 pounds (91 kg) So, US men are about larger than US women by about 15% for both height and weight. If humans had the proportions of hawks then the men would be 5’3 and the women 6’8", and the men would weigh 170 pounds and the women 220 pounds. In such a world rape in the sense of man inserting his penis into the woman against her will would probably be much more unlikely, and that’s the world birds live in. Also, outside of waterfowl, chickens, and a very few others male birds don’t have a penis and as already noted require cooperation from the female to complete the act. Rinse and repeat. “Traumatic insemination” seems to be most common among insects and snails, but isn’t universal there.

Dolphins are known for attempting to copulate with just about anything. It’s not uncommon for two males to herd a female in heat away from the pod and have her to themselves. How much cooperation is involved vs. coercion I don’t think anyone really knows for sure.

Can rape result in offspring? Sure. But it’s not the slam dunk it first appears to be. If it was every species would be doing it.

In particular, with humans, we know that penis-in-vagina can result in a baby six months later, thereby giving a woman the option to destroy the child if she unwants it enough, for her husband to destroy it, or for the society she lives in to destroy it. This has been the case for quite a long time. So forced copulation in humans is, arguably, less likely to result in an offspring than other mammals.

If the female is willing then it is NOT rape, it is NOT sexual assault, and the example does not apply. Female chimpanzees in heat happily pull trail with every male in the group. If anyone gets hurt it’s males who fight over access to the female.

16

True. I wonder in species (like the robin, mentioned, or chickens and roosters) how the need for a male to defend a territory and mate affect this statistic. Large males in mammals tends to correlate with the level of combat between males for control of females.

Also, some bird species the male “puts on a show” for the female who then decides which male has the best genes acceptable for her offspring. (Hence peacocks, among many others) Naturally, if a species also has males that will force themselves on an unwilling female, that defeats the entire purpose of the display process and negates the value of display.

IIRC, for a lot of species where male display and female selection is a reproductive strategy, the logic is that the male does not stay to help raise the offspring, so a physical demonstration of good genes is the only contribution the the survival of his offspring. (Although distinctive coloration is also a feature that says “yes, you got the right species of male”)

Certainly humans have abortion as an option nowadays; it does not appear to have been the norm for much of history. Sex at the right time, forced or not, has a possibility of producing offspring (Diamond goes into detail about huidden fertility and its significance in humans). does have the chance of reproduction. Of course, it’s difficult to separate the reproductive motivation from the pleasure motivation for sex. Given the prevalence and use of contraception, it seems pleasure (and self-gratification) is a dominant driver.

Analogously, but less controversial - do people overeat to the point where it’s a serious problem because they are driven by hunger, or by the pleasure derived from eating food? It’s hard to separate the two motivations, it’s a proportion of both - but I would guess, mostly pleasure.

17

Also social bonding.

Also, it’s not just contraception; humans not only have hidden fertility, we really aren’t very fertile in the first place. Even if the couple has sex at the right time there’s only about a 30% chance of pregnancy. Species that just have sex to reproduce tend to be much more fertile; such as cattle that only have sex during mating season and have up to a 60% impregnation chance.

So yes; we’ve clearly evolved for “recreational sex” to be the norm rather than the exception.

18

Diamond speculated that hidden fertility (and enjoyment) encouraged the male to stay around and help provide for the female and (his) children. As anyone who listens to music on the radio (or streamed) can tell, our brains are heavily wired for this sort of pair bonding.

Humans are almost reverting to marsupial status, in that children are born very early (before the baby’s head gets too big to fit through the pelvis) and then are relatively helpless for the next year or two and need constant nurturing. This is probably a reason why humans tend to not be excessively fertile. Note too, breastfeeding is supposed to suppress fertility, to also space out the timing of offsping - but it is not recommended as the only means of birth control. (Other mammals have offspring who are born premature, and left in a nest or den, but generally these tend to be because they are producing large litters.)

Another question, to get back to the OP - why would a female decline to have sex with a male? It possibly depends on how advanced the species is, and it’s unlikely they uderstand the link between sex and offspring, and so unlikely to be not wanting offspring at the time. But if, say, the role of the female is -as so often - to select the mate with the best genes, a species where the males negate this process is not in Mother Nature’s (or the species’) best interest. Similarly, a male that will force itself on a female despite the female already pair-bonded with another male is also contrary to that instinct in the species. Rape can be destructive in evolutionary terms too.

19

Just as another example, in many species of mustelid, the female won’t ovulate unless ‘induced’, which entails the male violently biting the female and throwing/dragging her around. It looks anything but consensual, however it is not just crucial for reproduction but also for the general health of the female.